How to Adjust the Carburetor for a Craftsman Chainsaw

Craftsman manufactures a wide variety of small engine products, from leaf blowers and chainsaws up to larger riding lawn tractors. Craftsman chainsaws have a two-cycle engine that combines oil and gasoline to burn as fuel. The carburetor takes the mixture and controls the amount of fuel and air going to the engine, causing the engine to increase or decrease in speed. As the engine begins to wear, the performance of the chainsaw may decline. Adjust the carburetor, to allow the chainsaw to operate at peak performance.

Step 1

Place the chainsaw on a flat surface.

Step 2

Locate the three carburetor adjustment screws on the side of the starting cord and fan housing. The top two screws will be marked "H" and "L." "L" is the low-speed adjustment and the "H" is the high-speed adjustment. The screw located below the "H" and "L" screws is the idle adjustment marked "I."

Step 3

Turn both the "H" screw and "L" screw clockwise just until they stop turning; do not over tighten. Turn both screws counter-clockwise one full turn.

Step 4

Start the chainsaw and allow the engine to idle for two minutes. If the engine sputters or is idling to low, slowly turn the "I" screw clockwise until the engine is running smoothly. If the engine is idling to high, slowly turn the "I" screw counterclockwise until the engine runs smoothly.

Step 5

Adjust the "L" screw while the engine is still running. Slowly turn the "L" screw clockwise until the engine's RPMs drop. Note the position of the screw. Slowly turn the "L" screw counter-clockwise until the engine RPMs speed up then drops again. Note the position of the screw. Set the "L" screw in between the two noted points.

Step 6

Make a test cut on a piece of wood. If the saw seems to lose power through the cut, or smokes, adjust the "H" screw clockwise 1/16 of a full turn and make another cut. Keep adjusting by 1/16 turn until the saw cuts through the wood smoothly and without smoking.